[tex] \sqrt{45 {}^{2} - 27 {}^{2} } = \sqrt{(45 - 27) \times (45 + 27)} = \sqrt{18 \times 72} = \sqrt{1296} = 36[/tex]
√(45²-27²)=√(45+27)(45-27)=√(72×18)=√(18²×2²)=√36²=36
